Regional unicorns: Mistmane's kin
  
They have pointed and curved horns while most Equestrian unicorns have straight and smoothed horns. 

Regional pegasi: Elliptical wings. Example: Comparison between Pinkie Pie and Rainbow Dash's gen 5 "concept art"  
Pinkie is shown to have elliptical wings, which are shorter or stubbier than most wing types.

Regional earth ponies: Clydesdales. Example: Troubleshoes Clyde and/or Rockhoof
 

They start off like any other young pony/stallion, except with a big head and hooves despite being lanky. Sudden and/or rapid growth spurt.

Let me know what you think.